Bee

Morphology of a bee: hive-dwelling
social insect which produces honey and wax, see also carpenter
bee.Head: foremost part.Thorax: central part.Abdomen: rear part.Wing: appendage of a bee used for aerial locomotion.Segment: part of the abdomen.Hind leg: rear limb.Nail: pointed nail of a bee.Middle leg: middle limb.Fore leg: front limb.Spur: projecting part of the foreleg of a bee.Tarsus: each of the parts that make up the segment of the bee's
leg below the tibia.Tibia: central part of the bee's leg.Femur: first part of the bee's leg.Mouth parts: parts of the mouth.Compound eye: complex sight organ.Antenna: touch organ of a bee.

Photo :

EN : Bumblebee

FR : Bourdon

ES : Abejorro

A bumblebee or bumble bee is any member
of the bee genus Bombus, in the family Apidae; there are over 250 known
species primarily occurring in the Northern Hemisphere.

Bumblebees are social insects
that are characterized by black and yellow body hairs, often in bands.
However, some species have orange or red on their bodies, or may be
entirely black. Another obvious, but not unique, characteristic is the
soft nature of the hair (long, branched setae), called pile, that covers
their entire body, making them appear and feel fuzzy. They are best
distinguished from similarly large, fuzzy bees by the form of the female
hind leg, which is modified to form a corbicula; a shiny concave surface
that is bare, but surrounded by a fringe of hairs used to transport
pollen, in similar bees, the hind leg is completely hairy, and pollen
grains are wedged into the hairs for transport.

Like their relatives the honey bees, bumblebees
feed on nectar and gather pollen to feed their young.

The blood or hemolymph, as in other arthropods,
is carried in an open circulatory system. The body organs, "heart"
(dorsal aorta), muscles, etc. are surrounded in a reservoir of blood.
The dorsal aorta does pulse blood through its long tube, though, so
there is a circulation of sorts.

In fertilised queens the ovaries are activated
and when the queen lays her egg it passes along the oviduct to the vagina.
In the vagina there is a container called the spermatheca. This is where
the queen stored sperm from her mating. Before she lays the egg she
will decide whether to use sperm from the spermatheca to fertilise it
or not. Non-fertilised eggs grow into males, and only fertilised eggs
grow into females and queens.

As in all animals hormones play a big
role in the growth and development of the bumblebee. The hormones that
stimulate the development of the ovaries are suppressed in the other
female worker bees while the queen remains dominant. Salivary glands
in the head secrete saliva which is mixed with the nectar and pollen.
Saliva is also mixed into the nest materials to soften them. The fat
body is a nutritional store; before hibernation queens eat as much as
they can to enlarge their fat body, and the fat in the cells is used
up during hibernation.

Like all bee tongues, the bumblebee tongue
(the proboscis) is composed of many different mouthparts acting as a
unit, specialised to suck up nectar via capillary action. At rest or
when flying the proboscis is kept folded under the head. The abdomen
is covered with dorsal tergites and ventral sternites. Wax is secreted
from glands on the sternites.

The brightly-coloured pile of the bumble
bee is a form of aposematic signal. Depending on the species and morph,
these colours can range from entirely black, to bright yellow, red,
orange, white, and pink. Thick pile can also act as insulation to keep
the bee warm in cold weather. Further, when flying a bee builds up an
electrostatic charge, and as flowers are usually well grounded, pollen
is attracted to the bee's pile when it lands. When a pollen covered
bee enters a flower,
the charged pollen is preferentially attracted to the stigma because
it is better grounded than the other parts of the flower.

A bumblebee does not have ears, and it
is not known whether or how a bumblebee could hear sound waves passing
through the air, however they can feel the vibrations of sounds through
wood and other materials.

Bumblebees are typically found in higher
latitudes and/or high altitudes, though exceptions exist (there are
a few lowland tropical species). A few species (Bombus polaris and B.
alpinus) range into very cold climates where other bees might not be
found; B. polaris can be found in northern Ellesmere Island, the northernmost
occurrence of any eusocial insect,
along with its parasite, B. hyperboreus. One reason for this is that
bumblebees can regulate their body temperature, via solar radiation,
internal mechanisms of "shivering" and radiative cooling from
the abdomen, called heterothermy. Other bees have similar physiology,
but it has been best studied in bumblebees.

Bumblebees form colonies. These colonies
are usually much less extensive than those of honey bees. This is due
to a number of factors including: the small physical size of the nest
cavity, the fact that a single female is responsible for the initial
construction and reproduction that happens within the nest, and the
restriction of the colony to a single season (in most species). Often,
mature bumblebee nests will hold fewer than 50 individuals, and may
be within tunnels in the ground made by other animals, or in tussock
grass. Bumblebees sometimes construct a wax canopy ("involucrum")
over top of their nest for protection and insulation. Bumblebees do
not often preserve their nests through the winter, though some tropical
species live in their nests for several years, and their colonies can
grow quite large, depending on the size of the nest cavity. The last
generation of summer includes a number of queens who overwinter separately
in protected spots. The queens can live up to one year, possibly longer
in tropical species.

Bumblebee nests are first constructed
by over-wintered queens in the spring, in temperate areas. Upon emerging
from hibernation, the queen collects pollen and nectar from flowers
and searches for a suitable nest site. The characteristics of the nest
site vary among bumble bee species, with some species preferring to
nest in underground holes and others in tussock grass or directly on
the ground. Once the queen has found a site, she prepares wax pots to
store food and wax cells into which eggs are laid. These eggs then hatch
into larvae, which cause the wax cells to expand isometrically into
a clump of brood cells.

These larvae need to be fed both nectar
for carbohydrates and pollen for protein in order to develop. Bumblebees
feed larvae nectar by chewing a small hole in the brood cell into which
nectar is regurgitated. Larvae are fed pollen in two ways, depending on
the bumblebee species. So called "pocket-maker" bumblebees create
pockets of pollen at the base of the brood cell clump from which the larvae
can feed themselves. Conversely, "pollen-storer" store pollen
in separate wax pots and feed it to the larva in the same fashion as nectar.
Bumble bees are incapable of trophallaxis, direct transfer of food from
one bee to another.

With proper care, the larvae progress
through four instars, becoming successively larger with each molt. At
the end of the fourth instar the larvae spin silk cocoons under the
wax covering the brood cells, changing them into pupal cells. The larvae
then undergo an intense period of cellular growth and differentiation
and become pupae. These pupae then develop into adult bees, who chew
their way out of the silk cocoon. When adult bumble bees first emerge
from their cocoons, the hairs on their body are not yet fully pigmented
and are a greyish-white colour. The bees are referred to as "callow"
during this time, and they will not leave the colony for at least 24
hours. The entire process from egg to adult bee can take as long as
five weeks, depending on the species and the environmental conditions.

After the emergence of the first or second
group of workers, workers take over the task of foraging and the queen
spends most of her time laying eggs and caring for larvae. The colony
grows progressively larger and at some point will begin to produce males
and new queens. The point at which this occurs varies among species
and is heavily dependent on resource availability and environmental
factors. Unlike the workers of more advanced social insects, bumble
bee workers are not physically reproductively sterile and are able to
lay haploid eggs that develop into viable male bumble bees. Only fertilized
queens can lay diploid eggs that mature into workers and new queens.

Early in the colony cycle, the queen bumble
bee compensates for potential reproductive competition from workers
by suppressing their egg-laying by way of physical aggression and pheromonal
signals. Thus, the queen will usually be the mother of all of the first
males laid. Workers eventually begin to lay males later in the season
when the queen's ability to suppress their reproduction diminishes.
The reproductive competition between workers and the queen is one reason
that bumble bees are considered "primitively eusocial".

New queens and males leave the colony
after maturation. Males in particular are forcibly driven out by the
workers. Away from the colony, the new queens and males live off nectar
and pollen and spend the night on flowers or in holes. The queens are
eventually mated, often more than once and search a for suitable location
for diapause.

Bumblebees generally visit flowers exhibiting
the bee pollination syndrome. They can visit patches of flowers up to
1-2 kilometres from their colony. Bumblebees will also tend to visit
the same patches of flowers every day, as long as nectar and pollen
continue to be available. While foraging, bumblebees can reach ground
speeds of up to 15 m/s (54 km/h).

When bumblebees arrive at a flower, they
extract nectar using their long tongue "glossa" and store
it in their crop. Many species of bumblebee also exhibit what is known
as "nectar robbing": instead of inserting the mouthparts into
the flower normally, these bees bite directly through the base of the
corolla to extract nectar, avoiding pollen transfer. These bees obtain
pollen from other species of flowers that they "legitimately"
visit.

Pollen is removed from flowers deliberately
or incidentally by bumblebees. Incidental removal occurs when bumblebees
come in contact with the anthers of a flower while collecting nectar.
The bumblebee's body hairs receive a dusting of pollen from the anthers
which is then groomed into the corbiculae "pollen baskets".
Bumblebees are also capable of buzz pollination.

In at least a few species, once a bumblebee
has visited a flower, it leaves a scent mark on the flower. This scent
mark deters visitation of the flower by other bumblebees until the scent
degrades.. It has been shown that this scent mark is a general chemical
bouquet that bumblebees leave behind in different locations (e.g. nest,
neutral and food sites), and they learn to use this bouquet to identify
both rewarding and unrewarding flowers. In addition, bumblebees rely
on this chemical bouquet more when the flower has a high handling time
i.e. it takes a longer time for the bee to find the necta).

Once they have collected nectar and pollen,
bumblebees return to the nest and deposit the harvested nectar and pollen
into brood cells, or into wax cells for storage. Unlike honey bees,
bumblebees only store a few days' worth of food and so are much more
vulnerable to food shortages. However, because bumblebees are much more
opportunistic feeders than honey bees, these shortages may have less
profound effects. Nectar is stored essentially in the form it was collected,
rather than being processed into honey as is done in honey bees; it
is therefore very dilute and watery, and is rarely consumed by human.

Bumblebees of the subgenus Psithyrus (known
as cuckoo bumblebees, and formerly considered a separate genus) are
a lineage which has lost the ability to collect pollen, and live parasitically
in the colonies of other bumblebees. Before finding and invading a host
colony, a Psithyrus female (there is no caste system in these species)
will feed directly from flowers. Once she has infiltrated a host colony,
the Psithyrus female will kill or subdue the queen of that colony and
forcibly (using pheromones and/or physical attacks) "enslave"
the workers of that colony to feed her and her young. The female Psithyrus
also has a number of morphological adaptations, such as larger mandibles
and a larger venom sac that increase her chances of taking over a nest.
Upon hatching, the male and female Psithyrus disperse and mate. Like
non-parasitic bumblebee queens, female Psithyrus find suitable locations
to spend the winter and enter diapause upon being mated.

Carpenter bees are large, hairy bees distributed
worldwide. There are some 500 species of carpenter bee. Their name comes
from the fact that nearly all species except those in the subgenus Proxylocopa,
which nest in the ground, build their nests in burrows in dead wood,
bamboo, or structural timbers. Members of the related tribe Ceratinini
are sometimes referred to as "Small Carpenter Bees". A few
species bore holes in wood dwellings and earn the enmity of some homeowners,
though others regard them as pets.

In several species, the females live in
tunnels alongside their own daughters or sisters, creating a sort of
social group. They use wood bits to form partitions between the cells
in the nest. A few species bore holes in wood dwellings. Since the tunnels
are near the surface, structural damage is generally minor or nonexistent.
Carpenter bees can be important pollinators on open-faced flower,
even obligate pollinators on some, such as the Maypop (Passiflora incarnata),
though many species are also known to "rob" nectar by slitting
the sides of flowers with deep corollas. In the United States, there
are two eastern species, Xylocopa virginica, and Xylocopa micans, and
three other species that are primarily western in distribution, one
being Xylocopa varipuncta. X. virginica is by far the more widely distributed
species.

Some are often mistaken for a bumblebee
species, as they can be similar in size and coloration, though most
carpenter bees have a shiny abdomen, while in bumblebees the abdomen
is completely clothed with dense hair. Males of some species have a
white or yellow face, where the females do not; males also often have
much larger eyes than the females, which relates to their mating behavior.
Male bees are often seen hovering near nests, and will approach nearby
animals. However, males are harmless since they do not have a stinger.
Female bees do have a stinger, but are not aggressive, and will not
sting unless directly provoked.